1. Field of the Invention
The present invention relates to the fields of chemistry and medicine. More particularly, the present invention relates to certain oxazolidinone, imidazolidinone, and thiazolidonone analogs and use of those analogs in anti-cancer and anti-microbial pharmaceuticals.
2. Description of the Related Art
Cancer is a leading cause of death in the United States. Despite significant efforts to find new approaches for treating cancer, the primary treatment options remain surgery, chemotherapy and radiation therapy, either alone or in combination. Surgery and radiation therapy, however, are generally useful only for fairly defined types of cancer, and are of limited use for treating patients with disseminated disease. Chemotherapy is the method that is generally useful in treating patients with metastatic cancer or diffuse cancers such as leukemias. Although chemotherapy can provide a therapeutic benefit, it often fails to result in cure of the disease due to the patient's cancer cells becoming resistant to the chemotherapeutic agent. Due, in part, to the likelihood of cancer cells becoming resistant to a chemotherapeutic agent, such agents are commonly used in combination to treat patients.
Similarly, infectious diseases caused, for example, by bacteria are becoming increasingly difficult to treat and cure. For example, more and more microorganisms, such as bacteria, are developing resistance to current antibiotics and chemotherapeutic agents. Examples of such bacteria include both gram positive and gram negative bacteria, including Staphylococcus, Streptococcus, Mycobacterium, Enterococcus, Corynebacterium, Borrelia, Bacillus, Chlamydia, Mycoplasma, and the like. Examples of Fungi include Aspergillus, Candida, Trichoderma, and the like. Examples of protozoa include Plasmodium and Acanthamoeba. 
Therefore, a need exists for additional chemotherapeutics and antimicrobial agents to treat cancer and infectious disease. A continuing effort is being made by individual investigators, academia and companies to identify new, potentially useful chemotherapeutic and antimicrobial agents.
Marine-derived natural products are a rich source of potential new anti-cancer agents and anti-microbial agents. The oceans are massively complex and house a diverse assemblage of microbes that occur in environments of extreme variations in pressure, salinity, and temperature. Marine microorganisms have therefore developed unique metabolic and physiological capabilities that not only ensure survival in extreme and varied habitats, but also offer the potential to produce metabolites that would not be observed from terrestrial microorganisms (Okami, Y. 1993 J Mar Biotechnol 1:59). Representative structural classes of such metabolites include terpenes, peptides, polyketides, and compounds with mixed biosynthetic origins. Many of these molecules have demonstrable anti-tumor, anti-bacterial, anti-fungal, anti-inflammatory or immunosuppressive activities (Bull, A. T. et al. 2000 Microbiol Mol Biol Rev 64:573; Cragg, G. M. & D. J. Newman 2002 Trends Pharmacol Sci 23:404; Kerr, R. G. & S. S. Kerr 1999 Exp Opin Ther Patents 9:1207; Frenz, J. L., Kohl, A. C. & R. G. Kerr 2004 Exp Opin Ther Patents 14:17; Moore, B. S 1999 Nat Prod Rep 16:653; Faulkner, D. J. 2001 Nat Prod Rep 18:1; Mayer, A. M. & V. K. Lehmann 2001 Anticancer Res 21:2489), validating the utility of this source for isolating invaluable therapeutic agents. Further, the isolation of novel anti-cancer and anti-microbial agents that represent alternative mechanistic classes to those currently on the market will help to address resistance concerns, including any mechanism-based resistance that may have been engineered into pathogens for bioterrorism purposes.